A wireless power transfer system includes a power transmission coil device and a power reception coil device, and implements wireless power transmission using electromagnetic induction, magnetic resonance, etc. between coils. Each of the coil devices has a coil and ferrite therein. The coil device is surrounded by a housing. For example, the housing includes a protective cover and an aluminum plate. For example, the wireless power transfer system is applied to a power feeding system of an electric vehicle. In this case, the power reception coil device is installed in the vehicle.
Technologies disclosed in Patent Literatures 1, 2, and 3 are known. In an apparatus disclosed in Patent Literature 1, an in-vehicle transducer corresponding to a power reception coil device is installed in a vehicle (chassis). Alternatively, the in-vehicle transducer is installed to protrude downward on a lower surface of a vehicle body. In an apparatus disclosed in Patent Literature 2, a bobbin that supports a secondary self-resonant coil corresponding to a power reception coil is attached to a vehicle by a fixing member connected to a flange portion thereof.
In an apparatus disclosed in Patent Literature 3, an aluminum substrate of a power reception unit is fixed to a lower portion of a moving body by a non-magnetic bolt through a bolt hole. An aluminum substrate of a power feeding unit is fixed to a road surface, etc. by a non-magnetic bolt through a bolt hole. A protective cover made of polycarbonate is fixed to the substrate by a non-magnetic bolt through a bolt hole. A spacer is provided between the protective cover and an insulating plate, and strength of the protective cover is increased by the spacer.